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Non-doped type white organic electroluminescent (EL) devices have the following structure ITO/m-MTDATA (30nm) /NPB (20-dnm) /rubrene (0.1nm) /NPB (dnm) /DPVBi (20nm) /TPBi (20nm) /Alq (10nm) /LiF/Al were fabricated. The EL spectrum of the devices are dependent on the d and when d=3, the CIE coordinates of the device were well within the white region for voltage raging from 3V to 15V. This device has a luminance of 18950cd/m2 at 15V and maximum power efficiency of 5.65cd/A at 6V.

A novel derivative of oligo(phenylenvinylene) (OPV), 2,5-diphenyl -1, 4-distyrylbenzene with two trans-double bonds (trans-DPDSB), is used as a blue emitting material in blue and white organic light-emitting devices (OLEDs). Blue devices with a configuration of indium-tin oxide (ITO)/N,N´-diphenyl-N,N´-bis(1-naphthyl)-(1,1´-biphenyl)-4,4´-diamine (NPB)/ trans-DPDSB / tris (8-hydroxyquinoline) aluminum (Alq3)/LiF/Al are constructed, where NPB, Alq3 and trans-DPDSB are used as hole-transporting, electron-transporting and light-emitting layers, respectively. The color of emission is changed from blue-green to pure blue when the trans-DPDSB layer is thicker. By inserting an ultrathin 5,6,11,12-tetraphenylnaphthacene (rubrene) yellow light-emitting layer between the Alq3 and trans-DPDSB layers, white OLEDs are obtained. The maximum efficiency and luminance of the blue and white devices are 1.2, 3.0 cd/A, and 1400, 7000 cd/m2, respectively.

In this paper, we describe the performance of an organic light emitting devices〔OLEDs〕 with ITO /4,4’,4“-tris{N,- （ 3-methylphenyl ） -N-phenylamino}triphenylamine (m-MTDATA) /N,N-diphenyl-N,N-bis1-naphthyl-1,1-biphenyl-4,4-diamine (NPB) /copper phthalocyanine (CuPc) / NPB / Bathocuproine(BCP) / tris-8-hydroxyquinoline Aluminum (Alq3) / LiF/ AL structure, the CuPc inserted between the two layers of NPB as a hole-consuming layer (HCL), and the BCP as a hole-blocking layer (HBL) . The EL spectrum peak is at 430 nm, indicating that the carrier recombination is confined in the NPB layer, in additional light emission originates from NPB. Compared with the luminous efficiency of the conventional diode without CuPc layer, that of the diode with HCL has been sharply increased up to 2.62 cd /A. It suggested that the CuPc and BCP exactly function as hole-consuming and hole-blocking layers, respectively, which enhance the efficiency of carrier，s recombination and confine the excitation in the EL layer.

We have fabricated an organic light-emitting devices with high efficiency and brightness utilizing thick layer of a starburst amine compound 4,4’, 4’’-tris{N,-(3-methylphenyl)-Nphenylamin} triphenylamine (m-MTDATA) as hole injection buffer layer. The brightness and the current efficiency were comparatively improved compared with those of the device without the buffer layer. The device with 10nm m-MTDATA act as buffer layer has max brightness was 18590cd/m2 at 17 V, and the highest luminous efficiency was achieved 4.30cd/A, at 7V, which is nearly three times than that of the device without it.

we designed and fabricated a white organic light-emitting device based on{[2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9yl)ethenyl]-4H-pyran-4-ylidene] propane-dinitrile}ultrathin layer and 4,4 ´ -bis(2,2 ˊ diphenylvinyl)-1,1 ˊ -biphenyl. It shows a maximum power efficiency of 1.8l m/W at 4 V (the brightness is 51 cd/m2). Its brightness reaches 8496 cd/m2 at 16 V. And the chromaticity coordinates varying from (0.42,0.34) to (0.32,0.28) with the forward bias from 4 to 16 V are well within the white region.

The lifetime of organic light-emitting devices can be influenced by the OLED material and structure, electrode material, driving mode and so on. Among all these factors, OLED driving method has been regarded as one of the most important factors, and it is well known that ac-driving mode improves the lifetime of OLED, especially pulse-driving mode with a reversed-biased voltage on OLED. In this article, a new ac-driving mode for Active-Matrix OLED is proposed on basic fabrication of two-TFT current source pixel circuit. Simulation has been done on the pixel and 1×4 matrix circuits, and simulation results have demonstrated that OLED is in reversed-biased state during recovery time. At last, a practical peripheral circuit that can provide achieve an ac-driving mode has been designed.